Ways to debug failing tests

Problem/Motivation

I am writing FunctionalJavascript tests for this module listjs. The tests are running locally, I have tried both the methods as mentioned here https://www.drupal.org/docs/8/phpunit/phpunit-javascript-testing-tutorial, ad tests are passing for both the methods.

In the test setUp() I have written the code so that it downloads the library.

The tests are failing in the CI, you can see here https://www.drupal.org/pift-ci-job/623416. Seems like the test is not able to download the library.

Proposed resolution

Are there any ways to debug the tests?

Remaining tasks

N/A

User interface changes

N/A

API changes

N/A

Data model changes

N/A